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Workman HDX Auto Page 6 − 13 Electrical System
Rear Differential Lock Switch
The rear differential lock switch allows the rear axle dif-
ferential to be locked for increased traction or un − locked
for normal differential operation. The rear differential
lock switch is located on the dash (Fig. 13). An indicator
light on the differential lock switch identifies when the
rear differential is locked.
The differential lock mechanism is in the locked position
when the differential solenoid is de − energized. During
vehicle operation with the rear differential lock switch in
the normal position, the rear differential solenoid will be
energized by the circuit made through the switch and the
de − energized rear differential relay. This will allow the
rear wheels to rotate individually (unlocked). The indica-
tor on the differential lock switch will not be illuminated
when the switch is in the normal position.
When the rear differential lock switch is held in the mo-
mentary (locked) position, the circuit through the switch
and the de − energized rear differential relay will open.
This will cause the rear differential solenoid to de − ener-
gize, locking the rear differential and thus the rear
wheels. The indicator on the differential lock switch will
be illuminated when the switch is in the momentary posi-
tion.
NOTE: The rear differential lock switch can be used to
lock or unlock the differential while the vehicle is in mo-
tion.
If the parking brake is applied or the transmission is in
the neutral or park position while operating the vehicle
(ignition key in the RUN or START position), the rear dif-
ferential relay will be energized, opening the circuit and
de − energizing the rear differential solenoid and locking
the differential. This will ensure that the rear wheels are
locked when the vehicle is parked while running.
When the ignition switch is set to the OFF position, no
power is available to the circuit and the rear differential
solenoid will be de − energized, locking the differential.
This will ensure that the rear wheels are locked when the
vehicle is parked while OFF.
Testing
1. Park machine on a level surface, stop engine, apply
parking brake and remove key from ignition switch.
2. To ease access to differential lock switch, remove
hood of vehicle (see Hood in the Service and Repairs
section of Chapter 5 − Chassis).
3. Locate rear differential lock switch on dash and dis-
connect wire harness electrical connector from the
switch.
4. With the use of a multimeter (ohms setting), the rear
differential lock switch functions may be tested to deter-
mine whether continuity exists between the various ter-
minals for each switch position. The switch terminals are
marked as shown in Figure 14. The circuitry of this
switch is shown in the chart below. Verify continuity be-
tween switch terminals for each switch position.
SWITCH
POSITION
NORMAL
CIRCUITS
OTHER
CIRCUITS
NORMAL 2 + 1 5 + 4
MOMENTARY 2 + 3 5 + 6
5. Replace rear differential lock switch if testing proves
it to be faulty.
6. After testing, connect wire harness electrical connec-
tor to the rear differential lock switch.
7. Install hood if it was removed (see Hood in the Ser-
vice and Repairs section of Chapter 5 − Chassis).
1. Dash 2. Rear differential switch
Figure 13
1
2
Figure 14
BACK OF SWITCH
Electrical System